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 * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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 */

package javax.swing.plaf.synth;

import java.beans.*;
import javax.swing.*;
import javax.swing.plaf.*;
import java.awt.*;


/**
 * Provides the Synth L&amp;F UI delegate for
 * {@link javax.swing.JViewport}.
 *
 * @since 1.7
 */
public class SynthViewportUI extends ViewportUI
    implements PropertyChangeListener, SynthUI {

  private SynthStyle style;

  /**
   * Creates a new UI object for the given component.
   *
   * @param c component to create UI object for
   * @return the UI object
   */
  public static ComponentUI createUI(JComponent c) {
    return new SynthViewportUI();
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void installUI(JComponent c) {
    super.installUI(c);
    installDefaults(c);
    installListeners(c);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void uninstallUI(JComponent c) {
    super.uninstallUI(c);
    uninstallListeners(c);
    uninstallDefaults(c);
  }

  /**
   * Installs defaults for a viewport.
   *
   * @param c a {@code JViewport} object
   */
  protected void installDefaults(JComponent c) {
    updateStyle(c);
  }

  private void updateStyle(JComponent c) {
    SynthContext context = getContext(c, ENABLED);

    // Note: JViewport is special cased as it does not allow for
    // a border to be set. JViewport.setBorder is overriden to throw
    // an IllegalArgumentException. Refer to SynthScrollPaneUI for
    // details of this.
    SynthStyle newStyle = SynthLookAndFeel.getStyle(context.getComponent(),
        context.getRegion());
    SynthStyle oldStyle = context.getStyle();

    if (newStyle != oldStyle) {
      if (oldStyle != null) {
        oldStyle.uninstallDefaults(context);
      }
      context.setStyle(newStyle);
      newStyle.installDefaults(context);
    }
    this.style = newStyle;
    context.dispose();
  }

  /**
   * Installs listeners into the viewport.
   *
   * @param c a {@code JViewport} object
   */
  protected void installListeners(JComponent c) {
    c.addPropertyChangeListener(this);
  }

  /**
   * Uninstalls listeners from the viewport.
   *
   * @param c a {@code JViewport} object
   */
  protected void uninstallListeners(JComponent c) {
    c.removePropertyChangeListener(this);
  }

  /**
   * Uninstalls defaults from a viewport.
   *
   * @param c a {@code JViewport} object
   */
  protected void uninstallDefaults(JComponent c) {
    SynthContext context = getContext(c, ENABLED);
    style.uninstallDefaults(context);
    context.dispose();
    style = null;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public SynthContext getContext(JComponent c) {
    return getContext(c, SynthLookAndFeel.getComponentState(c));
  }

  private SynthContext getContext(JComponent c, int state) {
    return SynthContext.getContext(c, style, state);
  }

  private Region getRegion(JComponent c) {
    return SynthLookAndFeel.getRegion(c);
  }

  /**
   * Notifies this UI delegate to repaint the specified component.
   * This method paints the component background, then calls
   * the {@link #paint(SynthContext, Graphics)} method.
   *
   * <p>In general, this method does not need to be overridden by subclasses.
   * All Look and Feel rendering code should reside in the {@code paint} method.
   *
   * @param g the {@code Graphics} object used for painting
   * @param c the component being painted
   * @see #paint(SynthContext, Graphics)
   */
  @Override
  public void update(Graphics g, JComponent c) {
    SynthContext context = getContext(c);

    SynthLookAndFeel.update(context, g);
    context.getPainter().paintViewportBackground(context,
        g, 0, 0, c.getWidth(), c.getHeight());
    paint(context, g);
    context.dispose();
  }

  /**
   * Paints the border. The method is never called,
   * because the {@code JViewport} class does not support a border.
   * This implementation does nothing.
   *
   * @param context a component context
   * @param g the {@code Graphics} to paint on
   * @param x the X coordinate
   * @param y the Y coordinate
   * @param w width of the border
   * @param h height of the border
   */
  @Override
  public void paintBorder(SynthContext context, Graphics g, int x,
      int y, int w, int h) {
  }

  /**
   * Paints the specified component according to the Look and Feel.
   * <p>This method is not used by Synth Look and Feel.
   * Painting is handled by the {@link #paint(SynthContext, Graphics)} method.
   *
   * @param g the {@code Graphics} object used for painting
   * @param c the component being painted
   * @see #paint(SynthContext, Graphics)
   */
  @Override
  public void paint(Graphics g, JComponent c) {
    SynthContext context = getContext(c);

    paint(context, g);
    context.dispose();
  }

  /**
   * Paints the specified component. This implementation does nothing.
   *
   * @param context context for the component being painted
   * @param g the {@code Graphics} object used for painting
   * @see #update(Graphics, JComponent)
   */
  protected void paint(SynthContext context, Graphics g) {
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void propertyChange(PropertyChangeEvent e) {
    if (SynthLookAndFeel.shouldUpdateStyle(e)) {
      updateStyle((JComponent) e.getSource());
    }
  }
}
